C.G.
I had the same troubles with my son before we finally got him fully potty trained. What I finally had to do was take a week off from work and be at home with him all day everday to get him to do it. A power struggle with a 2 year old is fruitless so my best advice is be patient and try not to get frustrated. Children have control over very little aside from when and where they go potty so what seems like stubborn refusal is probably just a control issue. I know it was with my son. Also remember you have a new baby in the house and this may cause her to regress a little. Patience it the only advice I have for you. Good Luck!!!